The present invention relates to a gas discharge display panel, such as a plasma display, and, more particularly, to an AC driving type gas discharge display panel having a high contrast. The invention also relates to a manufacturing method for a gas discharge display panel and to a display unit, such as a monitor, using a gas discharge display panel.
A gas discharge display panel, such as a plasma display, produces a display by its own light emission, so that the view angle is wide and the display is clearly visible. It has characteristics such that a thin panel can be produced and a large screen can be realized, and so application of a gas discharge display panel to a display unit of an information terminal device, a high-quality TV receiver, and similar display devices can be expected.
Gas discharge display panels are broadly divided into the DC driving type and the AC driving type. The AC driving type plasma display panel has a memory function by the action of a dielectric covering the electrodes and the brightness thereof is high. Recently, by application of a protective film, a life span fit for practical use has been realized and the AC driving type panel has been put to practical use as a multipurpose video monitor.
FIG. 9 shows a partial perspective view of the structure of a conventional plasma display panel. This gas discharge color display panel has a rear substrate 2 and a front substrate 1 which are arranged opposite to each other. The rear substrate 2 has a barrier rib 3a for maintaining the gap with the front substrate 1 constant, and the front substrate 1 and the rear substrate 2 are connected to each other via this barrier rib 3a. In FIG. 9, the front substrate 1 and the barrier rib 3a of the rear substrate 2 are separated from each other for ease of illustration of the structure.
The front substrate 1 has display electrodes (transparent electrodes) 61 and 71, bus electrodes 62 and 72, a dielectric layer 8, and an MgO film (protective film) 9 formed on a front glass plate 4. The rear substrate 2 has an address electrode 14, a barrier rib 3a, and a fluorescent layer 12 formed on a rear glass plate 5. The front substrate 1 and the rear substrate 2 are arranged and stuck in parallel relationships to each other so that the surfaces with electrodes face each other and a discharge space 3f is formed between the front substrate 1 and the rear substrate 2. The display electrodes 6 and 7 and the address electrode 14 are arranged on both sides of the discharge space 3f so as to cross at right angles.
Cross-sectional views of the gas discharge display panel are shown in FIGS. 10a to 10c and 22. FIG. 10a is a cross-sectional view of a part of the display panel of this embodiment as seen on a plane which is parallel with the address electrode 14 and perpendicular to the surfaces of the substrates 1 and 2. FIG. 10b is a cross-sectional view at the position 10B shown in FIG. 10a and the section thereof is on a plane which is perpendicular to the address electrode 14 and perpendicular to the surfaces of the substrates 1 and 2. FIG. 10c is a cross-sectional view at the position B shown in FIG. 10a and the section thereof is a plane which is perpendicular to the address electrode 14 and perpendicular to the surfaces of the substrates 1 and 2. In FIGS. 10a to 10c, only the sections are shown so as to make the drawings more easily understood, and the illustration of the constitution which will be seen behind each view is omitted. The cross-sectional view on the plane indicated by 22 shown in FIG. 10a is shown in FIG. 22.
As shown in FIGS. 10b and 10c, between the substrates 1 and 2, a display cell (also referred to as a discharge cell) is formed for each combination of the display electrodes 61 and 71 and the discharge space 3f is formed by both the substrates 1 and 2 and the barrier rib 3a. Inside this discharge cell, the fluorescent layer 12 is formed. The space 3f in the cell is charged with discharge gas. In this conventional display panel, as shown in FIG. 22, the barrier ribs 3a are parallel bar-shaped ribs, and the discharge spaces 3f of the cells which are continued transversely (or longitudinally) are not separated by the barrier ribs 3a. FIG. 22 is a parallel cross-sectional view of the discharge space.
When a pulse voltage is applied between the electrodes 6 and 7 of the front substrate 1 and the address electrode 14 formed on the rear substrate 2, an auxiliary discharge is generated in each cell formed by the front substrate 1, the rear substrate 2, and the barrier ribs 3a. On the surface of the protective layer 9 covering the parallel electrodes 6 and 7 formed in the front substrate 1 for each cell, a wall charge is formed using this auxiliary discharge. When a pulse voltage is applied between the electrodes 6 and 7 with the wall charge formed, a main discharge is generated. Ultraviolet light generated by this main discharge causes the fluorescent layer 12 coated inside each cell to emit light. The display of this display panel is realized by light from this fluorescent layer 12 which can be observed through the front substrate 1.
An example of the gas discharge display unit described above is set forth in Outsuka; Flat Panel Display 1994, pp. 198-201).
However, in the aforementioned publication, the display cells arranged in the extending direction of the address electrode 14 are separated only by the relative position of the display electrodes 6 and 7, and so, to prevent improper discharge between adjacent display cells, it is necessary to increase the distance between the display electrodes of adjacent display cells. The space between the display cells does not contribute to the display, but causes light blurring and color mixture by light emission of the existing fluorescent layer 12. The display electrodes 6 and 7 have the bus electrodes 62 and 72 for lowering the electrode resistance, and there exist many barrier ribs between the display cells arranged in the extending direction of the display electrodes. The bus electrodes are formed by an opaque material, so that they do not contribute to the display. The bad effect produced by the existence of the bus electrodes is increased when the electrodes are widened so that the electrode resistance is lowered. The existence of a portion around the display cells which does not contribute the display lowers the aperture ratio of the panel, so that a reduction in brightness is caused. Light emission between the display cells and the existence of the barrier ribs 11, which are not black, cause a reduction in the integrity of the black display status. In the display panel disclosed in the aforementioned publication, it is difficult to lower the brightness in the dark state and increase the brightness in the bright state, as mentioned above, and so a high contrast cannot be realized.